The hallmark of The Hell is a very serious approach to development. First and foremost, it is concentrated on getting rid of all the initial bugs of Diablo & Hellfire. It also raises challenge considerably, gives much more variety (monsters, items, spells, boss monsters, unique items, item & environment colors), improves overall difficulty balance of the game, improves monster AI, introduces new character animations, increases replay value and gives full support for Multiplayer experience. It is the HARDEST of Diablo Hellfire mods.
Nowadays version is fully functional, has many bugs of original game fixed, is running smooth, and on average is working way better than original game.
The amount of changes is tremendous (trust me), part of them are available in Changes Log file inside the game archive.

the original was supposed to have the speed of 8 frames, but they changed it to 7 frames in patch 1.1. which made it look choppy. I think it would be wise to fix that by the means of coding to retain 7 frame speed but make the animation look not cut (technically, cutting one frame not at the end, but in somewhere in the middle).